Direct Ingot Making of Titanium by Electro-winning from Molten Salt, Using Metal Pool of Titanium

本研究项目的目的是开发以钛金属池为阴极的电积钛直接制锭工艺。利用电渣重熔装置对过程热分析、电极反应机理和污染机理进行了研究。首先，测定了CaO-CaF_2-TiO_2渣系的电导率。二氧化钛的加入影响很小，电子传导可以忽略不计。通过用钢棒操作电渣重熔装置，阐明了熔池形状与电流-电压条件的关系。在电渣重熔的情况下，金属熔池不能在远高于纯钛熔点的温度下获得。结果表明，钛的熔点随着氧气的吸收而升高。因此，整个装置的气氛，特别是阴极部分，必须是内部的。在单电池操作中，…添加CaO-CaF_2-TiO_2渣后，最大阴极电流效率为12%，而阳极电流效率远低于100%。其原因可能是：1)在阳极上形成了钙的金属雾并进行二次氧化；2)钛与钛发生反应生成了Ti+-lt；4+-gt；2)在阳极上形成了Ti+-lt；2+-gt；因此，适当地控制电极间距和适当地控制二氧化钛含量是非常重要的。相反，通过在炉渣中加入三氧化二铝，可以提高熔炼效率。70克电沉积和C.A.阴极电流效率达到60%。究其原因，可能是因为熔渣的温度应通过添加剂来保持较高的温度，而铝沉积则是作为渣中Ti~(2+)的还原剂。该工艺有利于钛铝合金的生产，但不利于纯钛的生产，因为电沉积层中铝含量较高。它由双电池组成，其中一个是阳极槽，另一个是阴极槽，与熔盐桥相连。通过该装置，可以保持较长的阴阳极间距，从而提高电流效率，改善电沉积质量。该装置运行成功。因此，拟议的进程非常有前景。上述结果发表在6篇论文中。较少

The purpose of the present research project is to develop the direct ingot making process of titanium by electro-winning of titanium, where the metal pool of titanium is used as the cathode. By using ESR unit, the thermo-analysis of process, electrode reaction mechanism and contamination mechanism were examined.At first, the electrical conductivity of CaO-CaF_2-TiO_2 slag was measured. The effect of TiO_2 addition was so small that the electronic conduction could be neglected. Thus, the addition of TiO_2 to the slag was possible at relatively large amount.By operating ESR unit with steel rod, the relation between shape of metal pool and current-voltage condition was clarified. In the case of ESR, the metal pool could not be obtained at far higher temperature than the melting point of pure titanium. It was seen that the melting point of titanium rose by the absorption of oxygen. Thus, the atmosphere of the whole apparatus, especially, cathode part, must be innert.In the single cell oper … More ation with CaO-CaF_2-TiO_2 slag, the maximum cathodic current efficiency was 12%, and the anodic current efficiency was far less than 100%. The reasons must be 1) formation of metal fog of Ca and its re-oxidation at the anode, 2) formation of Ti^<2+> by the reaction of Ti with Ti^<4+> and its re-oxidation at the anode, and 3) formation of Ti^<2+> by the insufficient amount of Ca and its re-oxidation at the anode. Thus, it is important to control the electrodes distance properly and to control the TiO_2 content properly.On the contrary, by the addition of Al_2O_3 to the slag, c.a. 70 g of electro-deposit and c.a. 60% of cathodic current efficiency were obtained. The reasons must be that the temperature of molten slag should be kept higher temperature by the addition, and that the Al deposit should act as the reductant of Ti^<4+> in the slag. This process is good for producing Ti-Al alloy, but not good for producing pure Ti, because the electro-deposit contained much Al.On the base on the above results, the new apparatus was designed. It consists of twin cell, one of which is anode cell and the other, cathode cell, connected with molten salt bridge. By this apparatus, the distance between cathode and anode can be kept long, resulting in the larger current efficiency and better quality of electro-deposit. The apparatus was successfully operated. Thus, the proposed process is very promising. The above results are published in 6 papers. Less